Cho Minhaeng
Department of Chemistry and Center for Multidimensional Spectroscopy, Korea University, Seoul, Republic of Korea.
J Chem Phys. 2009 Mar 7;130(9):094505. doi: 10.1063/1.3079609.
A theoretical description of vibrational solvatochromism and electrochromism is presented by using a coarse-grained model based on a distributed charge and multipole interaction theory. Solvatochromic frequency shift has been described by considering the interaction between distributed charges of a solute and electrostatic potential due to distributed charges of solvent molecules. Another approach was based on the expansion of the solvatochromic frequency shift in terms of solvent electric field and its gradient at distributed sites on solute. The relationship between these two approaches is elucidated and their validities are discussed. It is also shown that the distributed charge and multipole model for solvatochromism developed here can be used to describe vibrational Stark effects on frequency and transition dipole moment. The relationship between the vibrational Stark tuning rate and the parameters obtained from recent vibrational solvatochromism studies is clarified and used to determine the vibrational Stark tuning rates of a few stretching modes, which are then directly compared with experimentally measured values. We anticipate that the present theoretical model can be used to study a variety of vibrational solvatochromic and electrochromic phenomena and to extract critical information on local electrostatic environment around a small IR probe in solution or protein from linear and nonlinear IR spectroscopic studies.
通过使用基于分布电荷和多极相互作用理论的粗粒度模型，对振动溶剂化显色和电致变色进行了理论描述。通过考虑溶质分布电荷与溶剂分子分布电荷产生的静电势之间的相互作用，描述了溶剂化显色频移。另一种方法是基于溶剂化显色频移在溶质分布位点处的溶剂电场及其梯度方面的展开。阐明了这两种方法之间的关系并讨论了它们的有效性。还表明，此处开发的用于溶剂化显色的分布电荷和多极模型可用于描述频率和跃迁偶极矩上的振动斯塔克效应。阐明了振动斯塔克调谐率与近期振动溶剂化显色研究获得的参数之间的关系，并用于确定一些拉伸模式的振动斯塔克调谐率，然后将其直接与实验测量值进行比较。我们预计，本理论模型可用于研究各种振动溶剂化显色和电致变色现象，并从线性和非线性红外光谱研究中提取有关溶液或蛋白质中红外小探针周围局部静电环境的关键信息。
